Laminar-turbulent transition in the boundary layer on cones in a hypersonic flow at high Reynolds numbers per meter

The laminar-turbulent transition is experimentally studied in boundary-layer flows on cones with a rectangular axisymmetric step in the base part of the cone and without the step. The experiments are performed in an A-1 two-step piston-driven gas-dynamic facility with adiabatic compression of the working gas with Mach numbers at the nozzle exit $\mathrm{M}_\infty=12-14$ and pressures in the settling chamber $P_0 = 60–600$ MPa. These values of parameters allow obtaining Reynolds numbers per meter near the cone surface equal to $\mathrm{Re}_{1e}=(53-200)\cdot10^6$ m$^{-1}$. The transition occurs at Reynolds numbers $\mathrm{Re}_{tr}=(2,3\div5,7)\cdot10^6$.